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I cannot find this book. (Reply)

I thought I'd bookmarked the review, to buy the book later, but apparently not. I've been through my browsing history for the past two months and ugh, maybe I'm looking right past it. I am left with no choice but to throw myself on the intarweebs and hope one of you might recognize this.

I think either historical fiction, or historical fantasy -- at the very least, alt-history. For some reason, I'm thinking renaissance era, like Venice or Milan (because apparently Italy was the entirety of the renaissance, but whatevs). The only plot-point I remember was that in this alt-history (or maybe secondary world altogether?) families could promise their daughters to a higher-born daughter, in a kind of promise/wedding. Sort of like being given as a companion.

And I remember thinking, that's a pretty cool change on things, I want to read that. Except now I can't for the life of me remember the title, or anything else pertinent, to google for it. Does this ring a bell for anyone else?